/*
 *    Copyright 2009-2012 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.io;

import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.Charset;
import java.util.Properties;

/**
 * A class to simplify access to resources through the classloader.
 * sss
 * @author Clinton Begin
 */
public class Resources {

    private static ClassLoaderWrapper classLoaderWrapper = new ClassLoaderWrapper();

    /*
     * Charset to use when calling getResourceAsReader. null means use the
     * system default.
     */
    private static Charset charset;

    Resources() {
    }

    /*
     * Returns the default classloader (may be null).
     *
     * @return The default classloader
     */
    public static ClassLoader getDefaultClassLoader() {
        return classLoaderWrapper.defaultClassLoader;
    }

    /*
     * Sets the default classloader
     *
     * @param defaultClassLoader - the new default ClassLoader
     */
    public static void setDefaultClassLoader(
            ClassLoader defaultClassLoader) {
        classLoaderWrapper.defaultClassLoader = defaultClassLoader;
    }

    /*
     * Returns the URL of the resource on the classpath
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static URL getResourceURL(
            String resource)
            throws IOException {
        return getResourceURL(null,
                resource); // issue #625
    }

    /*
     * Returns the URL of the resource on the classpath
     *
     * @param loader The classloader used to fetch the resource
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static URL getResourceURL(
            ClassLoader loader,
            String resource)
            throws IOException {
        URL url = classLoaderWrapper
                .getResourceAsURL(
                        resource,
                        loader);
        if (url == null)
            throw new IOException(
                    "Could not find resource "
                            + resource);
        return url;
    }

    /*
     * Returns a resource on the classpath as a Stream object
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static InputStream getResourceAsStream(
            String resource)
            throws IOException {
        return getResourceAsStream(
                null, resource);
    }

    /*
     * Returns a resource on the classpath as a Stream object
     *
     * @param loader The classloader used to fetch the resource
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static InputStream getResourceAsStream(
            ClassLoader loader,
            String resource)
            throws IOException {
        InputStream in = classLoaderWrapper
                .getResourceAsStream(
                        resource,
                        loader);
        if (in == null)
            throw new IOException(
                    "Could not find resource "
                            + resource);
        return in;
    }

    /*
     * Returns a resource on the classpath as a Properties object
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static Properties getResourceAsProperties(
            String resource)
            throws IOException {
        Properties props = new Properties();
        InputStream in = getResourceAsStream(resource);
        props.load(in);
        in.close();
        return props;
    }

    /*
     * Returns a resource on the classpath as a Properties object
     *
     * @param loader The classloader used to fetch the resource
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static Properties getResourceAsProperties(
            ClassLoader loader,
            String resource)
            throws IOException {
        Properties props = new Properties();
        InputStream in = getResourceAsStream(
                loader, resource);
        props.load(in);
        in.close();
        return props;
    }

    /*
     * Returns a resource on the classpath as a Reader object
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static Reader getResourceAsReader(
            String resource)
            throws IOException {
        Reader reader;
        if (charset == null) {
            reader = new InputStreamReader(
                    getResourceAsStream(resource));
        } else {
            reader = new InputStreamReader(
                    getResourceAsStream(resource),
                    charset);
        }
        return reader;
    }

    /*
     * Returns a resource on the classpath as a Reader object
     *
     * @param loader The classloader used to fetch the resource
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static Reader getResourceAsReader(
            ClassLoader loader,
            String resource)
            throws IOException {
        Reader reader;
        if (charset == null) {
            reader = new InputStreamReader(
                    getResourceAsStream(
                            loader,
                            resource));
        } else {
            reader = new InputStreamReader(
                    getResourceAsStream(
                            loader,
                            resource),
                    charset);
        }
        return reader;
    }

    /*
     * Returns a resource on the classpath as a File object
     *
     * @param resource The resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static File getResourceAsFile(
            String resource)
            throws IOException {
        return new File(getResourceURL(
                resource).getFile());
    }

    /*
     * Returns a resource on the classpath as a File object
     *
     * @param loader - the classloader used to fetch the resource
     *
     * @param resource - the resource to find
     *
     * @return The resource
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static File getResourceAsFile(
            ClassLoader loader,
            String resource)
            throws IOException {
        return new File(getResourceURL(
                loader, resource)
                .getFile());
    }

    /*
     * Gets a URL as an input stream
     *
     * @param urlString - the URL to get
     *
     * @return An input stream with the data from the URL
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static InputStream getUrlAsStream(
            String urlString)
            throws IOException {
        URL url = new URL(urlString);
        URLConnection conn = url
                .openConnection();
        return conn.getInputStream();
    }

    /*
     * Gets a URL as a Reader
     *
     * @param urlString - the URL to get
     *
     * @return A Reader with the data from the URL
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static Reader getUrlAsReader(
            String urlString)
            throws IOException {
        Reader reader;
        if (charset == null) {
            reader = new InputStreamReader(
                    getUrlAsStream(urlString));
        } else {
            reader = new InputStreamReader(
                    getUrlAsStream(urlString),
                    charset);
        }
        return reader;
    }

    /*
     * Gets a URL as a Properties object
     *
     * @param urlString - the URL to get
     *
     * @return A Properties object with the data from the URL
     *
     * @throws java.io.IOException If the resource cannot be found or read
     */
    public static Properties getUrlAsProperties(
            String urlString)
            throws IOException {
        Properties props = new Properties();
        InputStream in = getUrlAsStream(urlString);
        props.load(in);
        in.close();
        return props;
    }

    /*
     * Loads a class
     *
     * @param className - the class to fetch
     *
     * @return The loaded class
     *
     * @throws ClassNotFoundException If the class cannot be found (duh!)
     */
    public static Class<?> classForName(
            String className)
            throws ClassNotFoundException {
        return classLoaderWrapper
                .classForName(className);
    }

    public static Charset getCharset() {
        return charset;
    }

    public static void setCharset(
            Charset charset) {
        Resources.charset = charset;
    }

}
